抗炎 并不像某些人说的那么简单

Fighting Inflammation It's not as simple as some claim

 

 

心脏病，癌症，老年痴呆症，代谢综合症，身体残疾。这只是与慢性炎症有关的疾病的部分清单。

 

哈佛大学公共卫生学院(Harvard School of Public Health)营养系主任沃尔特•威利特(Walter Willett)解释说:“这不同于我们通常认为的那种典型的、红色、肿胀、白细胞的炎症。”

 

相反，它更多的是一种缓慢的燃烧，只能通过炎症信号的增加来检测，或者是免疫系统产生的用来对抗感染或治疗损伤的标记蛋白(尽管不是你能看到或感觉到的那种损伤)。问题是:你如何扑灭火焰?

 

到目前为止，只有一件事是明确的，威利特说。“减少炎症因素最有效的方法就是减肥。”

　

　

 

炎症的危害

从安德鲁(“消炎食物金字塔Anti-Inflammatory Food Pyramid”)、韦尔(“区域饮食The Zone Diet”)、西尔斯、尼古拉斯(“整容……”在你的厨房里Get a Face Lift...in Your Kitchen”)

你会认为，如果你吃了正确的食物，就很容易对抗炎症。

 

但炎症越少，疾病就越少，还是炎症只是一个小角色，还是一个无辜的旁观者? 如果抑制炎症很重要，如果有的话，食物能做到吗? 这两个问题的答案都难以捉摸。

 

心脏病

宾夕法尼亚州立大学的Penny Kris-Etherton解释说:“炎症在冠心病中起着两个重要的作用。”

首先，它有助于建立缩小动脉的斑块。这个过程始于免疫系统在动脉壁上动员起治疗“损伤”时，动脉壁的损伤通常由氧化的低密度脂蛋白胆固醇引起的。吸烟、高血压和高血糖也会损害动脉并导致斑块的形成。

 

 

克里斯-埃瑟顿说:“每一步，斑块中产生的炎症信号都会促进这个过程。”

经过几十年的研究，现在已经充满了胆固醇、钙和细胞的脂肪——被一层纤维状的平滑肌细胞覆盖。然后，再一次，炎症造成了严重破坏。

“炎症会导致不稳定斑块的破裂，从而导致血栓，”克里斯-埃瑟顿说。“这会阻碍血液流经动脉，从而导致心肌梗死、中风或周围动脉疾病。”

“所以炎症是非常重要的，”她补充道。用“饮食，生活方式，甚至低剂量的阿司匹林来控制它是绝对重要的。”

 

 

代谢综合征

令人震惊的是，五分之二的美国人患有代谢综合症，这增加了患心脏病和糖尿病的风险。如果你至少有以下三种:

血压:130 / 85以上

空腹血糖:100或更高

腰围:至少35英寸(女性)或40英寸(男性)

高密度脂蛋白胆固醇:低于50(女性)或40(男性)

甘油三酯:150或更高。

 

“代谢综合症显然是一种炎症状态，”加州大学戴维斯分校的伊什瓦尔拉尔•加勒尔(Ishwarlal Jialal)说。这是因为脂肪细胞向血液中喷射炎症标志物(见下图)。

“脂肪组织产生有害因素，如C反应蛋白、肿瘤坏死因子-阿尔法和白介素-1、6和8，”贾拉尔说。

　

他的新研究发现，这不仅是内脏(腹部)脂肪，而且是皮下脂肪(皮下脂肪)，这是罪魁祸首。“没有无辜的脂肪，”贾拉尔说。

一些同样的炎症标志物被脂肪细胞吐出来也会导致胰岛素抵抗——身体不能使用胰岛素来将血糖带入细胞——这就导致了糖尿病。

“这是一个非常重要的观察，”威利特说。

填充脂肪细胞和入侵的巨噬细胞发出白细胞介素-6、肿瘤坏死因子-阿尔法，以及其他导致炎症的信号。

　

　

图示：填充脂肪细胞和入侵的巨噬细胞发出白细胞介素-6、肿瘤坏死因子-阿尔法，以及其他导致炎症的信号。

　

 

癌症

“我们有证据表明局部炎症可能与癌症有关，”威利特说。一个典型的例子:当一种叫做幽门螺杆菌的细菌在胃里繁殖时，它会增加胃癌(和溃疡)的风险。

 

威利特指出:“感染引起炎症反应，导致细胞增殖，这可能是潜在的癌症过程的一部分。”

但是，即使细菌不是，炎症也可能与某些癌症有关。威利特说:“我们有确凿的证据表明，阿司匹林可以降低患结肠癌的风险，而且很可能是通过炎症途径。”

 

其他证据表明，炎症可能在肺癌、食道、子宫颈和肝脏的癌症中起作用。

这并不是说炎症与所有癌症有关。例如，“乳腺癌就不那么明显了，”威利特说。“炎症与炎症因素有关，但也与超重和肥胖有关，因此很难将炎症的影响与胰岛素抵抗的影响区分开来。”

 

事实上，两者都不是关键。“最明显的途径可能是雌激素，”威利特说，因为它能促进大多数乳腺肿瘤，而脂肪细胞是绝经后雌激素的主要来源。

 

记忆丧失

炎症与老年痴呆症有关的第一个线索来自尸检。

“在阿尔茨海默氏症患者的大脑中，beta-淀粉样蛋白斑块周围的炎症标志物浓度非常高，”哈佛医学院(Harvard Medical School)医学助理教授扎尔迪•谭(Zaldy Tan)说。

“现在有几项研究发现，循环炎症标志物水平较高的人患痴呆症的风险较高。”

　

一个例子:在Tan的研究中，在七八十岁的人群中，那些具有较高炎症标志物的人在接下来的七年里被诊断为阿尔茨海默氏症的几率是那些较低水平的人的两倍。

 

此外，“一些研究发现，由于关节炎或其他原因服用布洛芬和萘普生等消炎药的人患痴呆症的风险似乎更低，”Tan说。

 

然而，给有阿尔茨海默症风险的人服用抗炎药物的临床试验发现，他们的精神功能要么与服用安慰剂的人相同，要么下降得更厉害。

 

“如果你在一段时间内或者更早的时候给药，结果可能会不同，”Tan说。也有可能抑制炎症根本没有帮助。

“我们不知道炎症是痴呆症的起因还是结果，”Tan说。它可能只是免疫系统对-淀粉样斑块的反应。“炎症可能是罪魁祸首，也可能只是无辜的旁观者。”

 

残疾

随着年龄的增长，炎症会侵蚀你的肌肉。

北卡罗来纳州温斯顿-塞勒姆威克森林医学院老年医学教授芭芭拉·尼克拉斯解释说:“炎症和肌肉质量和力量的丧失之间有很强的联系。”

例如，在对2000名年龄在70岁到79岁之间的男性和女性进行的健康、衰老和身体组成研究中，那些炎症标志物水平较高的人在未来五年内更容易丧失大腿肌肉和握力。

“炎症标志物水平较高的人身体上的活动能力较差，”Nicklas说。

 

无论你的体重是多少，肌肉萎缩症都可能发生。“通常肥胖的人有更多的肌肉，因为他们必须承受体重，”Nicklas解释说。“但一个肥胖的人体内脂肪过多，肌肉过少。”这可能导致摔倒。

 

目前还不清楚为什么炎症标志物会随着年龄增长。一种可能性是:“随着年龄的增长，你会变胖，失去肌肉，不管你怎么努力，”Nicklas说。

她补充说，由于即将到来的疾病，炎症可能也会增加。“一些研究人员认为，随着年龄的增长，肠道、鼻子或其他器官的粘膜衬里会发生破坏，这就会导致体内出现更多的病原体，因此炎症会蔓延。”

 

但目前还不清楚炎症是导致肌肉萎缩，还是其他因素导致肌肉萎缩。Nicklas说，“我们不知道炎症是否是罪魁祸首。”

　

　

 图示：1。氧化的低密度脂蛋白胆固醇通过渗透入动脉壁上产生“损伤”。2。免疫系统会释放像单核细胞这样的炎性细胞来治愈伤口。3所示。单核细胞进入细胞壁，变成巨噬细胞，吞噬低密度脂蛋白胆固醇。4所示。填充LDL的巨噬细胞形成“脂肪条纹”。5 ”。几十年之后，更多的胆固醇、结缔组织、钙和细胞碎片聚集在一起，将条纹变成斑块。平滑肌细胞在斑块上形成纤维帽。6。巨噬细胞破坏帽。帽破裂。当血块在破裂处形成时，血流就会被阻断，从而引发心脏病或中风。

　

　

什么可以帮助

减肥和锻炼

不管你是通过减少卡路里，锻炼，还是两者兼有来减肥。如果你体重增加了，失去它们可以抑制炎症。“体重是一个重要因素，”哈佛大学的Walter Willett说。

 

锻炼呢?尼克拉斯说:“对于正常的、健康的普通人来说，体育锻炼对炎症并没有什么影响。”

她补充说:“只有两种方法可以让锻炼减轻炎症。”一种是通过运动减肥。

　

第二点:“如果你一开始就发炎，那么锻炼也会有好处。”Nicklas说。“如果你患有关节炎、心力衰竭或其他慢性疾病，或者你的炎症标志物处于正常的较高水平。”

 

这包括许多老年人。在她对424名年龄在70岁到89岁之间的人进行的研究中，那些每周做几次有氧、力量、平衡和柔韧性运动的人的白介素含量在一年后降低了。

 

但是，在你冲出去参加5公里赛跑之前，请三思。Nicklas警告说:“一次高强度的锻炼会增加炎症。”“对于老年人来说，炎症可能导致全身肌肉衰竭和疲劳。”

但这不是坐在沙发上的理由。

“如果你坚持锻炼，”Nicklas说，“炎症的程度并没有那么严重，因为你的健康状况更好。”你的肌肉越来越强壮了。

 

不管你的年龄如何，锻炼可以降低患心脏病、糖尿病、结肠癌和乳腺癌、虚弱等等的风险。

“没有药物可以维持肌肉量，”Nicklas说。“在任何年龄，你唯一能做的就是力量训练。”

 

ω- 3和ω- 6脂肪酸

为什么欧米伽-3脂肪酸——像鱼油中的EPA和DHA或者亚麻籽中的ALA——会减缓发炎呢?

南达科他州桑福德医学院的威廉·哈里斯解释说:“这要追溯到一种观点，即欧米茄-6脂肪酸可以产生具有促炎作用的类花生酸。”(玉米、大豆和葵花籽油富含-6脂肪酸。)

 

他补充说:“欧米伽-3脂肪酸可以产生自己的类花生酸，这一结果更加友善和温和。”

 

这就是为什么omega-3脂肪酸具有抗炎的名声。哈里斯说，在一些风湿性关节炎的临床试验中也发现了这种现象，在这些试验中，炎症非常猖獗，而且“相对高剂量的omega-3脂肪酸可以减少关节酸痛”。

 

一开始，有证据表明-3脂肪酸还能抑制炎症程度较低的人的炎症，这似乎是有希望的。

 

哈里斯说:“研究发现，摄入omega-3脂肪酸的人体内的炎症标志物水平较低。”但是当研究人员给有或没有心脏病的人服用omega-3时，炎症并没有改变。

 

“在大多数研究中，他们在随机试验中给人们提供鱼油，并没有降低炎症标志物，”Harris承认，他也是一家测量红细胞中omega-3含量的公司的总裁和首席执行官。“有相反的例子，但这是通常的经验。”

 

目前还不清楚为什么。哈里斯建议说:“要改变这些标记，可能需要多年的高摄入量。”“或者是吃更多鱼的人对其他生活方式因素更谨慎，”这就是为什么他们的炎症更少。

 

另一种可能性是:也许这些研究并没有衡量正确的东西。

宾州州立大学的Penny Kris-Etherton说:“如果你接触到细菌或病毒，你需要炎症反应，因为它有助于治疗和对抗感染。”“只有当炎症持续很长一段时间后才会造成严重破坏。”

 

因此，她正在开展一项新的研究，以测试人体对感染的反应。“我们给人们提供EPA和DHA”——鱼油中的omega-3——“在很长一段时间内以不同的剂量给他们注射，然后以非常、非常低的剂量给他们注射大肠杆菌，”她解释说。

 

问题是:“如果你用-3脂肪酸使你的细胞和细胞膜过饱和，那么这不仅能抑制炎症反应，还能加快解决问题的速度吗?”

 

鱼油可以保护心脏，不管炎症是否起作用。在意大利的一项试验中，鱼油降低了第二次心脏病发作的风险。在日本对18000名服用降胆固醇药物的人进行的试验中，EPA帮助了那些甘油三酯高、高密度脂蛋白胆固醇低的人。“他们患心脏疾病的风险降低了50%，”哈里斯说。

 

鉴于这些试验和其他证据，美国心脏协会建议每个人每周至少吃两次富含脂肪的鱼。

你是否也需要减少油中含有的-6脂肪酸?不，哈里斯主持的心脏协会小组说。

 

“少吃OMEGA-6脂肪并没有意义，”哈里斯说。身体并没有把它转化成炎性的类花生酸。“所以整个人体——少吃植物油，就能少吃炎症性的花生酸——是错误的。”

 

但是吃更多的omega-3脂肪酸可能会有帮助，因为这意味着“将会生产出较少的omega-6基的炎性eicosanoids”，Harris补充道。

 

其他食物

地中海饮食。意大利研究人员让180名患有代谢综合症的人吃地中海式饮食(富含水果、蔬菜、全谷物、豆类和橄榄油，低饱和脂肪)，或者听从“健康食品选择”的建议。

 

两年后，地中海组的一些炎症标志物水平较低，但这可能是因为它们的体重减轻了。

 

橄榄油和坚果 在西班牙一项针对大约100名有心血管疾病风险的人的研究中，那些被要求多吃橄榄油或坚果的地中海饮食者的炎症指标比那些不吃橄榄油或坚果的人下降得更多。但其他研究的结果却不尽相同。

 

全谷类食品 在三项研究中，被分配吃全麦食物的人的炎症指标并不比那些吃精制谷物的人低。

 

水果和蔬菜  在德国的一项研究中,男性被告知每天吃8份水果和蔬菜的低水平的炎症标志物C反应蛋白(CRP)比告诉每天吃2份的低, 

但是差异一方面是由于2-serving组的CRP水平升高。另一项研究发现，当超重的绝经后妇女被告知每天吃2份、5份或10份蔬菜时，CRP没有变化。

 

豆类  在西班牙一项针对30名肥胖男女的研究中，那些被告知每周要减少热量摄入并吃四份(每一份约为一杯)小扁豆、鹰嘴豆、豌豆或豆类的人的CRP水平低于那些不吃豆类而减少热量摄入的人。(吃豆制品的人体重减轻了很多，但研究人员对此进行了调整。)

 

但是，这些都不足以证明，豆类——或者任何食物——都是重要的。

 

“我不建议仅仅根据一两个研究或单独的观测数据做出决定，”美国农业部人类营养研究中心的心血管营养实验室主任艾丽丝·利希滕斯坦说。

 

底线是:用豆类、水果、蔬菜、全谷物和鱼来代替肉类、糖果和精制谷物——用油代替黄油和人造黄油——是明智的，即使它丝毫不会改变你的炎症标记。

 

“你能通过饮食改变炎症吗?”“数据是模棱两可的。你可以通过减肥来改变它。而且，还有很多其他的好理由可以让大多数美国人减肥。

 

 

 

　

 

Fighting Inflammation It's not as simple as some claim

November 1, 2011

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Heart disease, cancer, Alzheimer’s disease, the metabolic syndrome, physical disability. That’s just a partial list of the illnesses that have been linked to chronic inflammation.

 

"It’s different from the classic, red, swelling, white-cell kind of inflammation that we’re used to thinking of," explains Walter Willett, chair of the Nutrition Department at the Harvard School of Public Health.

 

Instead, it’s more of a slow burn that’s detected only by a rise in inflammatory signals, or markers—proteins produced by the immune system to fight infection or heal an injury (though not the kind of injury you can necessarily see or feel). The question is: how can you douse the flames?

 

So far, only one thing is clear, says Willett. "The most powerful way to reduce your inflammatory factors is to lose excess weight."

 

Inflammations's Harm

Judging by the advice from Andrew ("Anti-Inflammatory Food Pyramid") Weil, Barry ("The Zone Diet") Sears, Nicholas ("Get a Face Lift...in Your Kitchen?") Perricone, and others, you’d think that if you ate the right foods, it would be easy to fight inflammation.

 

But does less inflammation mean less disease, or is inflammation just a bit player or an innocent bystander? And if curbing inflammation matters, which, if any, foods can do it? The answers to both questions are elusive.

 

Heart Disease

"Inflammation plays two key roles in coronary heart disease," explains Penny Kris-Etherton of Pennsylvania State University.

 

First, it helps build the plaque that narrows arteries. The process starts when the immune system mobilizes to heal an "injury" in the artery wall, often caused by oxidized LDL cholesterol. Smoking, high blood pressure, and high blood sugar can also damage the arteries and lead to plaque buildup. (See illustration, p. 10.)

 

"And every single step of the way, inflammatory signals produced in the plaque fuel the process," says Kris-Etherton.

 

After decades, the plaque—now filled with cholesterol, calcium, and cell debris—gets covered with a fibrous cap of smooth muscle cells. Then, once again, inflammation wreaks havoc.

 

"Inflammation causes ruptures of unstable plaque, which results in a clot," says Kris-Etherton. "That can block the flow of blood through the arteries, which can lead to a myocardial infarction, a stroke, or peripheral artery disease."

 

"So inflammation is very significant,” she adds. Controlling it with “diet, lifestyle, and maybe even low-dose aspirin is absolutely important."

 

Metabolic Syndrome

An astounding two out of five Americans have the metabolic syndrome, which raises the risk of heart disease and diabetes. That includes you if you have at least three of the following:

 

blood pressure: 130 over 85 or higher

fasting blood sugar: 100 or higher

waist: at least 35 inches (women) or 40 inches (men)

HDL ("good") cholesterol: below 50 (women) or 40 (men)

triglycerides: 150 or higher.

"The metabolic syndrome is clearly an inflammatory condition," says Ishwarlal Jialal of the University of California, Davis. That’s because fat cells spew inflammation-causing markers into the bloodstream (see illustration below).

 

"Adipose tissue produces noxious factors like C-reactive protein, tumor necrosis factor-alpha, and interleukin-1, 6, and 8," says Jialal.

 

His new study found that it’s not just visceral (deep belly) fat, but also subcutaneous (under-the-skin) fat, that’s to blame. "There is no innocent fat," notes Jialal.

 

Some of those same inflammatory markers that are spit out by fat cells also cause insulin resistance—the body’s inability to use insulin to admit blood sugar into cells—which leads to diabetes.

 

“That’s a fundamentally important observation,” says Willett.

 

 

Stuffed fat cells and invading macrophages send out interleukin-6, tumor necrosis factor-alpha, and other signals that cause inflammation.

 Cancer

"We have evidence that local inflammation can be related to cancer," says Willett. A prime example: when a bacterium called Helicobacter pylori colonizes the stomach, it boosts the risk of stomach cancer (and ulcers).

 

"The infection causes an inflammatory reaction and that leads to cell multiplication, which may be part of the underlying cancer process," notes Willett.

 

But inflammation may be involved in some cancers even when bacteria aren’t. “We have definitive evidence that aspirin reduces colon cancer risk, and it’s very likely through inflammatory pathways,” says Willett.

 

Other evidence suggests that inflammation may play a role in cancers of the lung, esophagus, cervix, and liver.

 

That’s not to say that inflammation is linked to all cancers. For example, "it’s less clear for breast cancer," says Willett. "There are associations with inflammatory factors but also with overweight and obesity, so it’s difficult to separate the effect of inflammation from the effect of insulin resistance."

 

In fact, neither may be the key. "The clearest pathway is probably estrogen," says Willett, since it promotes most breast tumors, and fat cells are the chief source of estrogen after menopause.

 

Memory Loss

The first clue that inflammation is linked to Alzheimer’s disease came from autopsies.

 

"There is a very high concentration of inflammatory markers around the beta-amyloid plaques that are found in the brains of people with Alzheimer’s disease," says Zaldy Tan, assistant professor of medicine at Harvard Medical School.

 

"And now several studies have found that people with higher levels of circulating inflammatory markers are at increased risk of developing dementia."

 

One example: in Tan’s study of nearly 700 people in their 70s and 80s, those who had higher levels of inflammatory markers were twice as likely to be diagnosed with Alzheimer’s over the next seven years as those with lower levels.

 

What’s more, "some studies found that people taking anti-inflammatory drugs like ibuprofen and naproxen for arthritis or other reasons seemed to have a lower risk of developing dementia," says Tan.

 

However, clinical trials that gave anti-inflammatory drugs to people at risk for Alzheimer’s found that they had either the same or a greater decline in mental function as those who got a placebo.

 

"It’s always possible that if you give the drugs for a longer time or earlier in the disease, the results might be different," notes Tan. It’s also possible that curbing inflammation simply doesn’t help.

 

"We don’t know if inflammation is a cause or an effect of dementia," says Tan. It could simply be the immune system’s response to beta-amyloid plaques. "Inflammation could be a culprit or just an innocent bystander."

 

Disability

Inflammation may eat away at your muscles as you age.

 

"There’s a strong association between inflammation and a loss of muscle mass and strength," explains Barbara Nicklas, professor of geriatrics at Wake Forest Medical School in Winston-Salem, North Carolina.

 

For instance, in the Health, Aging, and Body Composition Study of 2,000 men and women aged 70 to 79, those with higher levels of inflammatory markers were more likely to lose thigh muscle and grip strength over the next five years.

 

"People with higher levels of inflammatory markers are less physically able to do things," says Nicklas.

 

And sarcopenia—muscle loss—can occur no matter what you weigh. "Usually people who are obese have more muscle because they have to carry the weight around," Nicklas explains. “But a sarcopenic obese person has a lot of fat and too little muscle.” And that can lead to falls.

 

It’s not clear why inflammatory markers go up with age. One possibility: "You gain fat and lose muscle as you age, no matter how hard you try," says Nicklas.

 

Inflammation may also rise because of impending illness, she adds. "And some researchers think that the mucosal linings of the gut or nose or other organs break down as we age, and that leads to more pathogens in the body, so inflammation creeps up."

 

But it’s still not clear if inflammation causes the loss of muscle or if something else causes both. Says Nicklas, "we don’t know if inflammation is the culprit."

 

 

1. Oxidized LDL cholesterol creates an “injury” by burrowing into the artery wall. 2. The immune system sends inflammatory cells like monocytes to heal the injury. 3. Monocytes enter the wall and turn into macrophages, which gobble up the LDL cholesterol. 4. The LDL-stuffed macrophages form a \"fatty streak.\" 5. Over decades, more cholesterol, connective tissue, calcium, and cell debris accumulate, turning the streak into plaque. Smooth muscle cells form a fibrous cap over the plaque. 6. Macrophages break down the cap. 7. The cap ruptures. When a clot forms around the rupture, blood flow is blocked, which triggers a heart attack or stroke.

What May Help

 

 

Weight Loss and Exercise

It doesn’t matter if you lose weight by cutting calories, exercising more, or both. If you’re carrying extra pounds, losing them can curb inflammation. "Weight is the big factor," says Harvard’s Walter Willett.

 

What about exercise? "For the normal, healthy, average person, exercise programs don’t really make a difference for inflammation," says Nicklas.

 

"There are only two ways in which exercise training will make a dent in inflammation," she adds. One is exercise that leads to weight loss.

 

The second: "Exercise may also have a benefit if you’re highly inflamed to start with," says Nicklas. "If you have arthritis or have heart failure or some other chronic condition, or if your inflammatory markers are at the higher end of normal."

 

That includes many older people. In her study of 424 people aged 70 to 89, those assigned to do aerobic, strength, balance, and flexibility exercises several times a week had lower levels of interleukin-6 after a year.

 

But think twice before you rush out to run that 5K race. "A single bout of exercise at a higher intensity increases inflammation," warns Nicklas. "In an older person, the inflammation may contribute to overall muscle breakdown and fatigue."

 

But that’s no reason to sit on the couch.

 

"If you keep up the exercise," notes Nicklas, "the amount of inflammation isn’t as bad, because you get better fitness. Your muscles are getting stronger."

 

And regardless of your age, exercise lowers the risk of heart disease, diabetes, colon and breast cancer, frailty, and more.

 

"There is no drug to maintain muscle mass," says Nicklas. "The only thing you can do at any age is strength train."

 

Omega-3 vs. Omega-6 Fats

Why would omega-3 fats—like the EPA and DHA in fish oil or the ALA in flaxseed—quiet inflammation?

 

"It goes back to the idea that the omega-6 fatty acids produce eicosanoids that have pro-inflammatory effects," explains William Harris of the University of South Dakota Sanford School of Medicine. (Corn, soybean, and sunflower oils are rich in omega-6s.)

 

"The omega-3 fats produce their own version of those eicosanoids, which are kinder and gentler," he adds.

 

That’s how omega-3s got their anti-inflammatory reputation. “And it’s been seen in some rheumatoid arthritis trials," where inflammation is rampant and "where relatively high doses of omega-3s reduce sore joints," says Harris.

 

At first, the evidence that omega-3s could also quell inflammation in people with lower levels of inflammation seemed promising.

 

"Studies found that people with higher omega-3 intakes had lower inflammatory marker levels," says Harris. But when researchers gave omega-3s to people with or without heart disease, inflammation didn’t budge.

 

"In the majority of studies where they’ve given fish oil to people in a randomized trial, it didn’t lower inflammatory markers," acknowledges Harris, who is also president and CEO of a company that measures omega-3 levels in red blood cells. "There are counter examples, but that’s the usual experience."

 

It’s not clear why. "It could take years of a high intake to change the markers," Harris suggests. "Or it could be that people who eat more fish are more careful about other lifestyle factors," and that’s why they have less inflammation.

 

Another possibility: maybe the studies aren’t measuring the right thing.

 

"If you get exposed to bacteria or a virus, you want an inflammatory response because it helps with healing and fighting the infection," says Penn State’s Penny Kris-Etherton. "It’s only when the inflammation smolders for a long time that it wreaks havoc."

 

So she’s launching a new study to test the body’s response to infection. "We’re giving people EPA and DHA"—the omega-3s in fish oil—"at different doses over a long period of time and then injecting them with E. coli bacteria at a very, very low dose," she explains.

 

The question: "If you supersaturate your cells and membranes with omega-3 fatty acids, will that not only quell an inflammatory response, but also quicken a resolution?"

 

Fish oil may protect the heart whether or not inflammation plays a role. In one Italian trial, fish oil lowered the risk of a second heart attack. And in a Japanese trial on 18,000 people who were taking cholesterol-lowering statin drugs, EPA helped those who had high triglycerides and low HDL ("good") cholesterol. "They had a 50 percent drop in risk of cardiac events," notes Harris.

 

In view of those trials and other evidence, the American Heart Association recommends that everyone eat fatty fish at least twice a week.

 

Do you also need to cut back on the omega-6 fats that are found in many oils? No, says the Heart Association panel that Harris chaired.

 

"Eating less omega-6 fat doesn’t make a difference," says Harris. The body doesn’t convert much of it to inflammatory eicosanoids. "So the whole mantra—eat less vegetable oil and you’ll make less inflammatory eicosanoids—is wrong."

 

But eating more omega-3s may help since it means that "less of the omega-6- based inflammatory eicosanoids will be produced," adds Harris.

 

Other Foods

Mediterranean diet. Italian researchers assigned 180 people with the metabolic syndrome to eat either a Mediterranean diet (rich in fruits, vegetables, whole grains, beans, and olive oil and low in saturated fat) or to follow advice on "healthy food choices."

After two years, the Mediterranean group had lower levels of several inflammatory markers, but that may be because they also lost more weight.

Olive oil & nuts. In a Spanish study of roughly 100 people at risk for cardiovascular disease, inflammatory markers dropped more in those assigned to eat a Mediterranean diet with extra olive oil or nuts than in those who ate the same diet without extra olive oil or nuts. But results from other studies differ.

Whole grains. In three studies, inflammatory markers were no lower in people assigned to eat whole grains than in those who got refined grains.

Fruits & vegetables. In a German study, men who were told to eat 8 servings of fruits and vegetables a day had lower levels of the inflammatory marker C-reactive protein (CRP) than those told to eat 2 servings a day, but the difference was partly due to a rise in CRP in the 2-serving group. Another study found no change in CRP when overweight postmenopausal women were told to eat 2, 5, or 10 servings of vegetables a day.

Legumes. In a Spanish study of 30 obese men and women, those told to cut calories and eat four servings (each about a cup) of lentils, chickpeas, peas, or beans a week had lower CRP levels than those who cut calories without eating legumes. (The bean eaters lost more weight, but the researchers adjusted for that.)

But none of that is enough evidence to be sure that beans—or any foods—matter.

 

"I wouldn’t recommend making a decision based on one or two studies or on observational data alone," says Alice Lichtenstein, director of the Cardiovascular Nutrition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.

 

The bottom line: replacing meats, sweets, and refined grains with beans, fruits, vegetables, whole grains, and fish —and substituting oils for butter and margarine—is smart, even if it doesn’t change your inflammatory markers one iota.

 

"Can you change inflammation with diet?" asks Lichtenstein. "The data are equivocal. You can change it by losing weight. And there are lots of other good reasons for the majority of Americans to lose weight."

https://cspinet.org/tip/fighting-inflamation